This invention relates generally to computers with graphic display systems, and more particularly to a graphic display used to determine interference between workpieces and their associated cutting tools as means to verify computer generated cutting tool paths.
For cutting irreqularly shaped parts such as turbomachinery elements, it is desirable to use complex cutting equipment wherein both the cutter and the workpiece holder may be movable about two or more axes simultaneously.
Often, interference between workpieces and cutters in numerically controlled cutters is determined by applying trial cuts to physical prototype workpieces, utilizing the actual cutting program which will be used to cut the final parts. However the considerable machine time required for the trial cuts, as well as the associated labor and material costs, often makes it desirable to simulate the trial cuts by illustrating the relationship between the cutter and the workpiece on a computer aided design/ computer aided manufacture (CAD/CAM) system.
Two common CAD/CAM methods which are presently applied in the above application are solid-shaded graphic display and wire frame graphic display methods.
The solid shaded graphic display utilizes a three dimensional graphic image which represents the shape of the original workpiece, even though the object is still displayed on a two dimensional graphic display terminal. The computer program input to the actual cutter and workpiece, along with the cutter tool physical parameters, determine the motion of the cutter and/or the workpiece, and modifies the shape of the image by subtracting primitive shapes from the image. The displayed shape reflects how the workpiece would be altered during each cutting step, thereby modelling the actual cutting process. From this, the final image will indicate whether any actual interference did occur during the machining process by showing cut edges.
The solid-shaded graphic displays are limited in that relatively sophisticated computer equipment is required to provide the shape and shading required for this type of display.
In wire frame systems, the final desired image of the workpiece is input into the computer. The path of the cutter as it shapes the workpiece, with respect to the shape of the final workpiece, is viewed to ensure that at no time during the cutting process of the workpiece will the cutting tool interfere with the actual final workpiece.
Wire frame technology also requires relatively complex computer hardware to operate. It is also often difficult to see whether an interference does exist between the workpiece and the cutter due to the complexity of the displays.
In both the solid-shaded and the wire frame type graphic displays, a large number of pixels are required to display the image. The large number of required pixels adds to the complexity of the display image.
The usual display method for both graphic display systems is to maintain a stationary workpiece image while the viewer observes an animated cutter tool image. Due to the positioning of the images on a two dimensional computer display screen, it is often impossible to determine whether an interference exists since the workpiece is displayed from only one view.
The foregoing illustrates limitations known to exist in present methods. Thus, it is apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.